Skype for Business crashes at sign-in after you apply the May 7, 2019 update

To fix this issue, install one of the following updates:

• For Skype for business 2016, install the June 4, 2019, update (KB4464576).

• For Skype for Business 2015 (Lync 2013), install the June 4, 2019, update (KB4464593).

Note Lync 2013 was upgraded to Skype for Business in April 2015.